Semiconductor laser device with multi-directional reflector arranged therein

Abstract

A microcavity semiconductor laser disclosed therein includes a double-heterostructure section including an intermediate active layer sandwiched between a first or lower cladding layer and a second or upper cladding layer above a semiconductive substrate. A first multi-layered reflector section is arranged between the substrate and the double-heterostructure section to have its reflectance which becomes maximum near the oscillation wavelength of the laser. The upper cladding layer is semi-spherically formed. A three-dimensional optical reflector covers the double-heterostructure section, for controlling spontaneous emission obtained in the double-heterostructure section along various directions, and for increasing the coupling ratio of spontaneous emission with a specific laser mode, thereby to decrease the threshold current.

What is claimed is: 
     
       1. A semiconductor laser device comprising: a semiconductive substrate having a surface;   a first distributed reflector section having two kinds of semiconductor layers which are different in refractive index from each other and are alternately laminated;   a double-heterostructure section including a first or lower semiconductive cladding layer and a second or upper cladding semiconductive layer separated by an intermediate active layer;   a second distributed reflector section on said double-heterostructure section with two kinds of semiconductor layers which are different in refractive index from each other and are alternately laminated;   said first reflector section, said double-heterostructure section, and said second reflector section having a projected structure with a side wall; and   a third distributed reflector section surrounding said side wall of said projected structure on said substrate and including two kinds of semiconductor layers which are different in refractive index from each other and are alternately laminated along a certain direction parallel with the surface of said substrate.   
     
     
       2. A laser according to claim 1, further comprising: insulator means for increasing electrical insulation between said first reflector section and said third reflector section.   
     
     
       3. A laser according to claim 2, wherein, said, second and third reflector sections define therebetween an interface region which is doped with an impurity. 
     
     
       4. A laser according to claim 3, further comprising: a conductive layer which at least partially covers said projected structure and said third reflector section.   
     
     
       5. A laser according to claim 4, wherein said second and third reflector sections include a proton-implanted region.